Subtraction by Rounding Worksheet

Mental maths lesson 21: Subtract by rounding up and adding back · Set 620 · 40 questions

How to do it in your head (Round up, add back): Round the number you take away up to the next ten or hundred: 297 → 300 (3 too many). Take away the round number. Add back the extra, because you took away too much.

1. 1.408 − 128 =
2. 2.781 − 239 =
3. 3.865 − 797 =
4. 4.746 − 697 =
5. 5.844 − 698 =
6. 6.863 − 558 =
7. 7.505 − 248 =
8. 8.570 − 497 =
9. 9.622 − 357 =
10. 10.743 − 199 =
11. 11.734 − 497 =
12. 12.961 − 617 =
13. 13.917 − 597 =
14. 14.962 − 269 =
15. 15.848 − 397 =
16. 16.934 − 297 =
17. 17.903 − 287 =
18. 18.449 − 299 =
19. 19.704 − 358 =
20. 20.846 − 507 =
21. 21.638 − 298 =
22. 22.963 − 499 =
23. 23.948 − 378 =
24. 24.664 − 497 =
25. 25.267 − 198 =
26. 26.782 − 697 =
27. 27.669 − 167 =
28. 28.507 − 397 =
29. 29.826 − 207 =
30. 30.992 − 619 =
31. 31.568 − 139 =
32. 32.728 − 598 =
33. 33.365 − 197 =
34. 34.287 − 189 =
35. 35.964 − 697 =
36. 36.428 − 297 =
37. 37.212 − 158 =
38. 38.583 − 249 =
39. 39.645 − 198 =
40. 40.224 − 198 =

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